a. Field of the Invention
The present invention relates to colloidal antimony oxide, and more specifically it relates to a chemically stable colloidal dispersion of antimony oxide which has been treated with a particular organosilicon compound and regulated to a particular pH range.
b. Description of the Prior Art
In order to make fabrics, fibers, plastics, etc. flame retardant, antimony oxide has been heretofore used together with halogen-containing substances such as organic chlorides, bromides, etc. However, in the case where the particle diameter of the antimony oxide is on the order of the size of pigments, i.e. from 0.5 to 5.mu., the touch, gloss, transparency, physical properties, etc. of the product are impaired. Therefore, several proposals have been made on the production methods of antimony oxide in fine particle form, as shown in Japanese Patent Publication No. 20479/1978, No. 11848/1982, Japanese Patent Kokai No. 123997/1977, etc.
By these methods it is possible to produce colloidal antimony oxide, but when it is dried by spray drying, etc., the primary particles agglomerate and unite, and therefore it is substantially impossible to take out dry powder in fine particle form.
On the other hand, even if it is attempted to use the antimony oxide as a colloidal dispersion, when an inorganic salt is present in the system which contains said dispersion or when the dispersion is mixed with vinyl chloride latex or vinylidene chloride latex, the colloidal particles will agglomerate and unite. Therefore, there is a great limitation in practical use, and problems in its application remain unsolved.
Colloidal antimony oxide, whose such problems have been entirely solved and which is especially chemically stable, can be provided by treating colloidal antimony oxide with an organosilicon compound represented by the following general formula: ##STR1## wherein R is a C.sub.1-8 substituent containing no amino group, mercapto group, methacryloxy group or halogen atom; each of R.sub.1 and R.sub.2 is a C.sub.1-4 substituent; and R.sub.3 is a C.sub.1-4 alkyl group, alkoxy-substituted alyl group or acetyl group, and by regulating the pH of the colloidal antimony oxide to within the range of from 2.5 to 12.